International Conference on Innovative Materials, Structures and Technologies
September 30-October 2 2015, Riga, Latvia
Cross-laminated timber is an environmentally friendly material, which possesses a decreased level of anisotropy in comparison with the solid and glued timber. Cross-laminated timber could be used for load-bearing walls and slabs of multi-storey timber buildings as well as decking structures of pedestrian and road bridges. Design methods of cross-laminated timber elements subjected to bending and compression with bending were considered. The presented methods were experimentally validated and verified by FEM. Two cross-laminated timber slabs were tested at the action of static load. Pine wood was chosen as a board's material. Freely supported beam with the span equal to 1.9 m, which was loaded by the uniformly distributed load, was a design scheme of the considered plates. The width of the plates was equal to 1 m. The considered cross-laminated timber plates were analysed by FEM method. The comparison of stresses acting in the edge fibres of the plate and the maximum vertical displacements shows that both considered methods can be used for engineering calculations. The difference between the results obtained experimentally and analytically is within the limits from 2 to 31%. The difference in results obtained by effective strength and stiffness and transformed sections methods was not significant.
The outcome of an experimental campaign on the long-term behaviour of timber floors retrofitted with timber-to-timber composite methods is presented. Four diaphragm specimens, 5.2 m long (5 m span) were tested out-ofplane. Each specimen consisted of a solid wood-spruce joist strengthened with a crosslam panel. A layer of timber boards was placed in between the joist and the panel to simulate the existing flooring. The specimens, were subjected to uniformly distributed loading in a climatic controlled chamber. A patented procedure that enables to apply a pre-stressed state and a pre-camber to the composite floor joists by just using screw fasteners, was adopted. Different typologies and arrangements of screws were tested in order to maximize the performance (cost/effectiveness) that can be achieved by employing the above mentioned procedure. Uplift values of approximately 1/300th of the diaphragm span were registered at the end of the cambering procedure. After an initial testing phase (duration approximately equal to 3h) where the loading was consistent with the characteristic combination, the specimens were set for long-term testing under an imposed load equal to that specified by the quasi-permanent combination.
This paper deals with stability analysis of clamped rectangular orthotropic thin plates subjected to uniformly distributed shear load around the edges. Due to the nature of this problem, it is impossible to present mathematically exact analytical solution for the governing differential equations. Consequently, all existing studies in the literature have been performed by means of different numerical approaches. Here, a closed-form approach is presented for simple and fast prediction of the critical buckling load of clamped narrow rectangular orthotropic thin plates. Next, a practical modification factor is proposed to extend the validity of the obtained results for a wide range of plate aspect ratios. To demonstrate the efficiency and reliability of the proposed closed-form formulas, an accurate computational code is developed based on the classical plate theory (CPT) by means of differential quadrature method (DQM) for comparison purposes. Moreover, several finite element (FE) simulations are performed via ANSYS software. It is shown that simplicity, high accuracy, and rapid prediction of the critical load for different values of the plate aspect ratio and for a wide range of effective geometric and mechanical parameters are the main advantages of the proposed closed-form formulas over other existing studies in the literature for the same problem.